University of the Algarve

About: University of the Algarve is a education organization based out in Faro, Portugal. It is known for research contribution in the topics: Population & Tourism. The organization has 3649 authors who have published 10303 publications receiving 233536 citations.

Light as a driver of phytoplankton growth and production in the freshwater tidal zone of a turbid estuary

Abstract: Light is usually the main driver of phytoplankton growth in turbid estuaries, but it has received far less attention than nutrients as a bottom-up factor. This study presents the first experimental analysis of light limitation of phytoplankton growth and production and its seasonal variability in the freshwater tidal reaches of the turbid Guadiana estuary, SE Portugal/SW Spain. Natural phytoplankton communities were exposed to different photosynthetically active radiation (PAR) intensities. Short-term incubations with addition of 14HCO3− were used to estimate photosynthetic parameters and long-term incubations allowed the evaluation of the effects of light on phytoplankton composition and growth. Light limitation of phytoplankton growth occurred throughout the year in the freshwater tidal reaches of the estuary and no photoinhibition was observed at least up to 615 μmol photons m−2 s−1. In the summer, co-limitation by nutrients prevented a positive response of phytoplankton to light enrichment. Diatoms were the most light-limited group, whilst cyanobacteria were the only group acclimated to low-light conditions. Green algae and dinoflagellates responded positively to higher PAR exposures. High saturating irradiances, high light-saturated rates of primary production and low photosynthetic efficiencies suggest that phytoplankton community was not acclimated to the low-light conditions that prevail in the Guadiana estuary.

The Tumorigenic Roles of the Cellular REDOX Regulatory Systems

Abstract: The cellular REDOX regulatory systems play a central role in maintaining REDOX homeostasis that is crucial for cell integrity, survival, and proliferation. To date, a substantial amount of data has demonstrated that cancer cells typically undergo increasing oxidative stress as the tumor develops, upregulating these important antioxidant systems in order to survive, proliferate, and metastasize under these extreme oxidative stress conditions. Since a large number of chemotherapeutic agents currently used in the clinic rely on the induction of ROS overload or change of ROS quality to kill the tumor, the cancer cell REDOX adaptation represents a significant obstacle to conventional chemotherapy. In this review we will first examine the different factors that contribute to the enhanced oxidative stress generally observed within the tumor microenvironment. We will then make a comprehensive assessment of the current literature regarding the main antioxidant proteins and systems that have been shown to be positively associated with tumor progression and chemoresistance. Finally we will make an analysis of commonly used chemotherapeutic drugs that induce ROS. The current knowledge of cancer cell REDOX adaptation raises the issue of developing novel and more effective therapies for these tumors that are usually resistant to conventional ROS inducing chemotherapy.

FOXO transcription factors at the interface of metabolism and cancer.

Abstract: Diabetes refers to a group of metabolic diseases characterized by impaired insulin signalling and high blood glucose. A growing body of epidemiological evidence links diabetes to several types of cancer but the underlying molecular mechanisms are poorly understood. The signalling cascade connecting insulin and FOXO proteins provides a compelling example for a conserved pathway at the interface between insulin signalling and cancer. FOXOs are transcription factors that orchestrate programs of gene expression known to control a variety of processes in response to cellular stress. Genes regulated by this family of proteins are involved in the regulation of cellular energy production, oxidative stress resistance and cell viability and proliferation. Accordingly, FOXO factors have been shown to play an important role in the suppression of tumour growth and in the regulation of metabolic homeostasis. There is emerging evidence that deregulation of FOXO factors might account for the association between insulin resistance-related metabolic disorders and cancer.

A reference growth curve for nutritional experiments in zebrafish (Danio rerio) and changes in whole body proteome during development

Abstract: Zebrafish is one of the most used vertebrate model organisms in molecular and developmental biology, recently gaining popularity also in medical research. However, very little work has been done to assess zebrafish as a model species in nutritional studies in aquaculture in order to utilize the method- ological toolbox that this species represents. As a starting point to acquire some baseline data for further nutritional studies, growth of a population of zebrafish was followed for 15 weeks. Furthermore, whole body proteome was screened during development by means of bi-dimensional gel electrophoresis and mass spec- trometry. Fish were reared under best practice labora- tory conditions from hatching until 103 days post- fertilization (dpf) and regularly fed ad libitum with Artemia nauplii from 12 dpf. A growth burst occurred within 9-51 dpf, reaching a plateau after 65 dpf. Fork length and body weight were significantly lower in males than in females from 58 dpf onwards. Proteo- mics analysis showed 28 spot proteins differently expressed through development and according to sex. Of these proteins, 20 were successfully identified revealing proteins involved in energy production, muscle development, eye lens differentiation, and sexual maturation. In summary, zebrafish exhibited a rapid growth until approximately 50 dpf, when most individuals started to allocate part of the dietary energy intake for sexual maturation. However, proteomic analysis revealed that some individuals reached sexual maturity earlier and already from 30 dpf onwards. Thus, in order to design nutritional studies with zebrafish fed Artemia nauplii, it is recommended to select a period between 20 and 40 dpf, when fish allocate most of the ingested energy for non-reproduc- tive growth purposes.

Transcriptome dynamics of a broad host-range cyanophage and its hosts.

Abstract: Cyanobacteria are highly abundant in the oceans and are constantly exposed to lytic viruses. The T4-like cyanomyoviruses are abundant in the marine environment and have broad host-ranges relative to other cyanophages. It is currently unknown whether broad host-range phages specifically tailor their infection program for each host, or employ the same program irrespective of the host infected. Also unknown is how different hosts respond to infection by the same phage. Here we used microarray and RNA-seq analyses to investigate the interaction between the Syn9 T4-like cyanophage and three phylogenetically, ecologically and genomically distinct marine Synechococcus strains: WH7803, WH8102 and WH8109. Strikingly, Syn9 led a nearly identical infection and transcriptional program in all three hosts. Different to previous assumptions for T4-like cyanophages, three temporally regulated gene expression classes were observed. Furthermore, a novel regulatory element controlled early-gene transcription, and host-like promoters drove middle gene transcription, different to the regulatory paradigm for T4. Similar results were found for the P-TIM40 phage during infection of Prochlorococcus NATL2A. Moreover, genomic and metagenomic analyses indicate that these regulatory elements are abundant and conserved among T4-like cyanophages. In contrast to the near-identical transcriptional program employed by Syn9, host responses to infection involved host-specific genes primarily located in hypervariable genomic islands, substantiating islands as a major axis of phage–cyanobacteria interactions. Our findings suggest that the ability of broad host-range phages to infect multiple hosts is more likely dependent on the effectiveness of host defense strategies than on differential tailoring of the infection process by the phage.